value || is not a member of When
[error] Note: implicit value whenFormat is not applicable here because it comes after the application point and it lacks an explicit result type
[error] Error occurred in an application involving default arguments.

I'd just like something that works, and I don't care what approach is used (even one I did not show), so long as it is maintainable and efficient. It would also be helpful to know what was wrong with each of these approaches.

gives you Reads[Long], then you can map result to When. You were just passing parameter. This parameter could be a Long, to just ignore what is read and return that value, or implicit reads for long that you probably don't want to change and should let it stay implicit.

So then in similar way you can create another reads for duration and combine them with alternative (|) and done, you have reads.

Your second approach makes no sense. Either use reads and compose them or just manually check if something is there and if not return a different result, but it is not worth doing this, just go with default approach.